Motor controller



Dec. 31, 1929. T, EVANS 1,741,762

MOTOR CONTROLLER Original Filed April 22, 1921 ZNVEN TOR. GXcl/Wvwe d. Ewan/1w ATTORNEY Patented Dec. 31, 1929 UNITED STATES PATENT orrlcr.

CLARENCE T. EVANS, OF WAUWA'IOSA, WISCONSIN, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO CUTLER-HAMMER ING, OF MILWAUKEE, WISCONSIN,' A CORPORATION OF DELAWARE MOTOR CONTROLLER Original application filed April 22, 1921, Serial No. 463,668. Divided and this application filed January 17, 1W7. Serial No. 161,596.

This invention relates to improvements in controllers for electric motors.

In my Patent No. 1,479,033 issued January 1, 192 1 there is disclosed a controller providing for acceleration of an electric motor subject to inductive time limit control, the arrangement being such as to insure against defeat of the accelerating operation of the controller by a high value of motor current, and the present invention relates to this general typeof control.

An object of the present invention is to providea controller of the aforesaid character wherein inductive time limit control is afiorded by relays, individual relays for each of a lurality of accelerating switches being provided to afford differentiation of adjustment of the controller 'for difierent steps of acceleration.

Another object of the invention is to provide a relay affording time limit control of the character aforestated, said relay having its contact actuating element in the magnetic field of only one winding and afiording a delay by the self inductance of such winding.

Other objects and advantages of the invention will hereinafter appear.

One embodiment of the present invention is illustrated in the accompanying drawing, and the same will now be described, it being understood that the embodiment illustrated is susceptible of various modifications without departing from the scope of the appended claims.

The drawing diagrammatically illustrates a form of controller disclosed in my copend ing application Serial hie. 463,668, filed April 22, 1921, of which the present application is a division.

Referring to the drawing, the same shows a direct current motor M which has been illustrated as com rising an armature A and a series field F. owever, it is to be understood that the motor may be of other types. The controller includes an electromagnetic main switch 1 to connect the motor across supply lines L and L through resistances R, R and R, and electromagnetic accelerating switches 2, 3 and 4 to short-circuit said resistances respectively.-

The switches 1 to i are electrically inten looked as hereinafter more fully set forth to respond sequentially, and accelerating sw1tches 2, 3 and A} are respectively provided with relays 5, 6 and 7 to time the response thereof. Each of these relays as will appear affords time limit control of its respective accelerating switch and current control to some extent. However, the relays are so designed as to terminate current control when the motor current ceases to change whereby defeat of acceleration'by a high value of motor current is precluded.

The, relays are of like construction, each comprising a fixed contact 8 and a cooperating contact 9 which is carried by a magnetic stood, when the winding 11 is subjected to a rising current it will act inductively on winding 12 to cause the latter to attract and hold its armature 10 whereas said armature will be released when the current through winding 11 ceases to rise subject, however, to a further delay by the self inductive effect of winding 12. The armature 10 of each relay carries a non-magnetic adjusting screw 14 to engage a pole of the magnetic frame to maintain a predetermined air gap between said pole and armature upon attraction of the latter and said armature is biased by a spring 15 to normally engage contact 9 with contact 8, the spring being preferably adjustable to valry the sensitiveness of response of the re a The winding 11 of each relay as will appear is subjected to the motor current and upon rise of the current traversing the same it acts inductively upon'winding 12 whereby the latter is caused to attract its armature 10.

dependent for energization upon closure of one of the switches 1 to 3 and more particularly the one preceding the switch controlled by such relay. Hence as each relay is normally closedit should be designed in accordance with well known-principles for quick response whereby it will open before the accelerating switch controlled thereby has an opportunity to close.

The power connections shown in the drawing may be traced as "follows: Upon response of main switch 1 circuit is completed from I line L through said switch by conductor 16 through the winding 11 of relay 5, by conductor 17 to and through resistances R, R and R in series, by conductor 18 through the motorvM to line L Upon response of accelerating switch 2 circuit may be traced from conductor 16 by conductor 19, through said accelerating switch, by conductor 20 to and through winding 11 of relay 6 to a point between resistances R and It, thus afiording a shunt for resistance R and the winding 11 of relay 5. Upon response of accelerating 35- switch-3 circuit may be traced from conductor 20, by conductor 21 to and through switch 3, by conductor 22 to and through the winding 11 of relafi 7 to a point between resistances R and thus'afiording a shunt for resistance R and winding 11 of relay 6. Upon response of accelerating switch 4 circuit is completed from conductor 22, by conductor 23 to and through switch 4, by conductor 24 to conductor 18 whereby resistance R is short-ci'rcuited together with the wind ing 11 of relay 7. Thus as above stated each of the relays is connected in circuit by the switch immediately preceding the switch controlled thereb The ,contro connections are as follows: The energizing circuit of main switch 1 extends from line L through a control switch 25 to and through the winding of said switch 1, by conductor 26 to line L The energizing c1rcuit of accelerating switch 2 extends from line L through auxihary contacts 1": of main switch 1, by conductor 27 through contacts 8 and 9 of relay 5, by conductor 28 to and through the winding of switch 2, by conductors 29 and 26 to lme L The energizing circuit of accelerating switch 3 is similarly controlled by auxiliary contacts 2 of accelerating switch 2 and the contacts of relay 6, while the energizing circuit of switch 4 is similarlv controlled by auxiliary contacts 3 of switch 3, and contacts of relay 7. Thus as above stated, the switches 1 to 4 are interlocked to insure response thereof sequentially.

Considering the operation of the controller it will be apparent that upon closure of main switch 1 to complete the motor circuit the relay 5 will open in response to the rise in the motor current from zero value and that when the motor current ceases to change or substantiall ceases to change the relay 5 will be permitted to reclose subject to a further delay by the self inductive action of its short-circuited winding 12 whereupon the first accelerating switch 2 will be energized. Thereupon relay 6 will be caused to respond, its winding 11 being now connected in series with the motor and bein subjected to a current rise from zero va ue. Onthe other hand, when the winding 11 of relay 6 receives the full motor current and the motor current substantially ceases to change the armature 10 of relay 6 will be released subject to a further delay by the self inductive action of its windin 12 whereu on the second accelerating switch 3 will e energized. This will cause relay 7 to function in a manner similar to relay 6 to energize the last accelerating switch 4 subject to a time element.

What I claim as new and desire to secure by Letters Patent is:

1. The combination with an electric motor, of a resistance therefor, a switch to complete the motor circuit through said resistance, electroresponsive accelerating switches to exclude said resistance from circuit in steps, a plurality of relays respectively controlling the energizing circuits of certain of said accelerating switches, said relays each having electroresponsive control meansand each having itscontact actuating part-in the magnetic,

field of one winding onl and connections whereby each relay is ren ered responsive to the current in the motor circuit to delay energization of its respective accelerating switch, each of said relavs after response being automatically rendered effective to energize its respective accelerating switch regardless of the instantaneous value of the motor current but subject to a time delay through self inductance of the aforementioned winding of therelay.

2. The combination with an electric motor, of resistance in circuit therewith, an electroresponsive switch to exclude said resistance and control means for said switch including an electroresponsive relay responsive to current in the motor circuit to delay response of said switch and releasable to render said switch responsive, said relay being operable by the magnetic pull of a single winding, and said winding having connections whereby it produces an inductive delay in the release of said relay.

of resistance in circuit therewith; an electroresponswe swltch to exclude sa1d resistance,

' and control means for said switch including an electroresponsive relay responsive to current: supplied to the motor todelay response of said switch and releasable regardless of the instantaneous value or the motor current to render said switch responsive, said relay having a magnetic Winding to produce a magnetic flux which alone is suficient to operate said relay, and said winding having connections causing it to produce an inductive delay in the release of said relay.

d. The combination with an electric motor, of resistance in circuit therewith, an electroresponsive switch to'exclude said resistance, and control means for said switch com rising an electroresponsive relay operable the magnetic pull of a single winding an supplied with motor current for efiecting its re sponse to delay response of said switch, said relay being releasable regardless of the instantaneous value of the motor current to render said switch-responsive but said winding having connections causing it to produce an inductive delay in the release of said relay.

5. The combination with an electric motor, of resistance in circuit therewith, an electroresponsive switch to exclude said resistance, and control means for said switch including an electroresponsive relay, said means being supplied with motor current for effecting re I sponse of said relay to delay response of said switch and said means having inductance to delay release of said relay, but said relay being releasable regardless of the instantaneous value of the motor current to efiect response of said switch.

6. The combination with an electric motor, of resistance 1n circuit therewith, and control means for said resistance comprising wind- -short-circuited windin a winding supplied with motor current an magnetic means placmg sa1d windings in an inductive relation 'and providing a magnetic circuit for said short-circuited winding separate from the magnetic circuit of theother of said windings,

responsive switch to exclude said resistance, and a control relay for said switch having a winding to be subjected to motor current, a short-circuited winding arranged in an in ductive relation with the former winding and a contact actuating element subjected to the magnetic pull of said short circuited winding Iii witness whereof, I have hereunto subscribed my name.

; CLARENCE T. EVANS.

and a contact actuatin element forming an armature in the magnetic circuit ofsaid shortcircuited winding only. r

8. The combination with an electric motor, of resistance in circuit therewith, an electro- 

